If you give a mouse a cookie, he'll ask you for a glass of milk. But, if you give a mouse chicken feed, fresh water, warm bedding, and a safe place to sleep, he'll make a home in your chicken coop, invite his friends, contaminate the feed and water, and introduce parasites and diseases to your chickens.
Like the boy in that adorable children's book, I don't get particularly squeamish from rodents like mice. Rats, on the other hand, no thank you! But together, those rodents can be vectors for nearly 50 different diseases affecting chickens and humans, most notably salmonella, and can also commonly carry mites into the coop. Infestations of rodents have been linked to both farm and house fires. Rats also love chicken eggs, and in extreme cases, they can even prey upon baby chicks or sleeping chickens. So, as cute as the field mice may be, its always best to keep them away from the coop.
Keep chicken feed and water out of reach. Chickens will give chase to rodents during the daytime, and they'll occasionally catch them successfully. Mice and rats, being nocturnal, will come to feast when the chickens are sound asleep, so it's best not to leave out a buffet for them.
Store bulk or bagged feed securely; think metal feed bins or locking metal trashcans. Mice can chew holes in feed bags, and even through plastic feed bins and trashcans.
Remove the chicken feed from the coop at night when you're out locking up the chickens and store it safely with the bagged feed in a metal container. Alternatively, you can suspend the feeder so it hangs to keep it off the ground. Rats can cling to rope or even chain, so smooth cable is the best choice. Treadle style feeders require a hen's weight to open and will easily keep mice from accessing the feed so you don't have to remove it from the coop nightly.
Clean up spilled feed.Even if you remove the feed every night, anything that's on the ground will be a gold mine for rodents. TIP: Switch to pellet feed to help prevent chickens from making a mess with their food.
Manual waterers make fresh water easy to access for rodents. Empty them nightly, and refill them with clean water in the morning for your chickens. Alternatively, switching to automatic watering systems like nipple waters will keep them from finding water in the coop.
Eliminate large holes or gaps in the coop. Rodents can chew through wood and plastic, and mice can squeeze through openings even smaller than one inch.
Use 1/2 inch hardware cloth or sheet metal to cover any large holes or gaps in the construction of your coop, and to enclose the run completely.
Bury wire around the perimeter of the coop and run to prevent rats from tunneling to get into the coop.
Tidy up the coop. Rodents thrive in messy, cluttered areas that don't see much activity. Keep the coop clean, and the area around the coop free of debris to eliminate places where rodents can make a nest.
Change the bedding regularly.
Store fresh bedding in a metal container.
Eliminate clutter and debris around the coop where rodents can hide.
Keep the grass mowed around the coop, and the weeds at bay.
Harvest eggs daily. Rats love chicken eggs, so leaving eggs in the nesting box overnight give them something to come for.
Use Mint. Mint grown around the coop or dried and used in the nesting boxes or bedding can help deter rodents from coming around the coop. It's important to note that this solution cannot be employed successfully on it's own, and should be used in tandem with good coop and flock management to experience true benefits. In addition to keeping the rodents away, mint can also benefit hens through aromatherapy.
Adopt a cat or dog. Even if the dog or cat doesn't hunt rodents, the smell of a larger animal in the area will help keep mice and rats at bay, as well as other larger predators on the hunt for chicken dinner. Just be careful not to adopt cats or dogs with a prey drive.
If prevention is unsuccessful, don't be hard on yourself. Although rodents do not always show up in areas with chickens, they are a natural cohabitant. There are plenty of ways to eliminate a rodent population but it's necessary to be very cautious with traps and poisons.